Is there any advantage to preallocate memory with Builder::with_capacity?

[surister]

Hi, I'm consuming async iterators that fetch data in row format and then transpose it to arrays with ArrayBuilders, I know the count beforehand so I thought that I could decrease max memory usage by pre-allocating, but I cant:

For example, I know I'm processing 14_996_513 rows:

• With Float64Builder::with_capacity(14_996_513) ~3259MiB
• With Float64Builder::new() ~2496MiB

[surister]

Actually, the number of values I was pushing to the array builders were always the allocated +1 due to another issue, I guess that triggers new allocation. With the right allocation number I get better numbers by using with_capacity as expected.